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Thread: Trajectory

  1. #1
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    Default Trajectory

    Hmm, I did some shooting up to 30 yards today and got one hell of a surprise when I decided to see what the trajectory looks like.

    The rifle is sighted for roughly 25 Yards.

    At 10 yards the grouping is 2" low

    At 15 yards the grouping is about 3/4 - 1" low

    At 20 yards the grouping is about 1/2" low

    At 25 yards the grouping is dead on

    At 30 Yards the grouping is 1/2 - 3/4" High

    Power/ speed is not an issue, the pellets punch straight through a 16mm Melamine board at any of the above distances, further to this the groupings stay tight and any deviation from the pattern is purely shooter error as I do not have an X-Bag or front rest, only a scatter cushion and a brick with a sock over it, perched on a wobbly table.

    Specs of the rifle, Pellets and telescope:
    Rifle: Webley Raider 10, Stock standard but not limited to 12FP energy.
    Scope: Nikko Stirling Night-Eater 3.5 - 10 X42 mounted on Gamo rings.
    Pellets: JSB Match Exact Diabolo 13.73 grain
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  2. #2
    Sharp Shooter

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    The way I see it is that the pellet is still on the rise up to the zero point where you r used to shooting and carries on doing so up to the peak of trajectory. Zeroed my scope once for 10m and at further distances kept shooting high. Never thought the pellet actually rises and then drops off. Or am I
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  3. #3
    Sharp Shooter

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    The trajectory you are suggesting is not possible, i think there was something that caused you to shoot higher at 30 yards.
    take a lazer, set it up so that it points 1" low at 20 yards and at zero at 25 , then it will be 1" high at 30. Its a straight line, pellets dont travel like that.

    To get even close to that trajectory you will have to have either 4" high mounts or doing more than 2000fps .

    Look for something that could have caused a point of impact change at longer distances. Low light conditions tend to make one shoot higher than normal, or a shiift in shooting position could have caused it.
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  4. #4
    Sharp Shooter

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    A trajectory will look like this.
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  5. #5
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    Quote Originally Posted by Bex View Post
    The trajectory you are suggesting is not possible, i think there was something that caused you to shoot higher at 30 yards.
    take a lazer, set it up so that it points 1" low at 20 yards and at zero at 25 , then it will be 1" high at 30. Its a straight line, pellets dont travel like that.

    This is what confuses me, it isn't supposed to happen this way.

    To get even close to that trajectory you will have to have either 4" high mounts or doing more than 2000fps .

    Look for something that could have caused a point of impact change at longer distances. Low light conditions tend to make one shoot higher than normal, or a shiift in shooting position could have caused it.

    You could be onto something here, at 30 yards the target was no longer in direct sunlight but in heavy shade under a tree. It makes sense now, come to think of it as I used to have to aim low when hunting rabbits at night.
    That sorts the last figures but I am still surprised at how much of a difference small increments in target distance makes on an air rifle's pellet trajectory.
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  6. #6
    Sharp Shooter

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    If youre serious about shooting you have to work out your rifle precisely. Set up yourself in good conditions with a good rest, 2 or 3 bags of beans or rice borrowed out of the pantry will work.
    Set up a target at 10m , shoot it and move to 15m . shoot it at every 5m out as far as ou can go, go to at least 50m though i would recomend 60m if you can find a big enough target. Mark your shots at each distance.

    It is important to do all this on your own so you can be relaxed , trying to rush this process wont work.

    Draw the results up in a graph so you can visualize it and draw it up in a table to use as "cheat sheet for shooting.
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  7. #7
    Sharp Shooter

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    A pellet drops a lot over distance, I know my TX200 when it was running at 790fps drops 3m at 145m.
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  8. #8
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    Quote Originally Posted by Bex View Post
    If youre serious about shooting you have to work out your rifle precisely. Set up yourself in good conditions with a good rest, 2 or 3 bags of beans or rice borrowed out of the pantry will work.
    Set up a target at 10m , shoot it and move to 15m . shoot it at every 5m out as far as ou can go, go to at least 50m though i would recomend 60m if you can find a big enough target. Mark your shots at each distance.

    It is important to do all this on your own so you can be relaxed , trying to rush this process wont work.

    Draw the results up in a graph so you can visualize it and draw it up in a table to use as "cheat sheet for shooting.
    Thank you very much for the advise. I will do this at some stage, just busy with wedding arrangements at the moment so will probably get around to it at the end of April.
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  9. #9
    Protea FT Team '11/'12/'13
    National FT Champ '12
    National FT Champ U17 '09/'10/'11/'12
    World FT Champ U17 '09/'11/'12

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    One word

    - Chairgun
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  10. #10
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    Quote Originally Posted by dutoitf View Post
    One word

    - Chairgun
    , Maybe its an age thing, I don't know what you mean?
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  11. #11
    Protea FT Team '12

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    Charigun is a ballistic software package for trajectory calculations for air rifles. It's availale from the Hawke website and is a nice tool to calculate/check your scope settings.
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  12. #12
    Prof. Jan Itor

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  13. #13
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    Quote Originally Posted by Jan The Man View Post
    Charigun is a ballistic software package for trajectory calculations for air rifles. It's availale from the Hawke website and is a nice tool to calculate/check your scope settings.
    Ahhh, ok got that. Thank you for the heads up.

    See it is an age thing, I can't keep up with these new fangled inventions anymore.
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  14. #14
    Sharp Shooter

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    Chairgun is a nice tool , but it is not a replacement for shooting to plot your trajectory.
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  15. #15
    Protea FT Team '12

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    I agree. What's the fun in sitting in front of a pc when you can be out shooting and learning your rifle's performance and quirks.
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